Swelling Of Mastoid Bone. On Antibiotics. Serious?

Hello, I previously had a swelling of my mastoid bone behind the right ear which was diagnosed as being caused by infected dandruff after an x ray. This was about ten years ago, and to be honest, I believe the bone has been somewhat swelled ever since. Just lately, I thought it had become slightly more swollen, although it is not bothering me or is not sore. Anyway after visiting my Doctor he initially puit me on antibiotics for ten days and now for a futher 12 days. He says he thinks there is an infection of the mastoid and that it is highly unlikely that it is being caused by dandruff.He said my ears are perfectly healthy. He said he hopes he does not have to send me for a mastoid bone operation. This is quite scaring me now. Is there anything wrong? Do I even need to be on antibiotics? I feel they are only making my face red and flushed. Surely, I would feel sick and the bone would be red and sore if I have a serious mastoid problem?